#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
#include<string>
using namespace std;
int main()
{
    string s;
    cin >> s;
    int n = s.size();
    int f = 1;
    for (int i = 0; i < n; i++)
    {
        if (s.substr(i, 3) == "ove" || s.substr(i, 3) == "lve" || s.substr(i, 3) == "loe" || s.substr(i, 3) == "lov")
        {
            cout << "YES" << endl;
            f = 0;
            break;
        }
    }
    if (f) cout << "NO" << endl;
    return 0;
}